# Pi(π) in C++ with Examples

In this article, we will discuss some of the mathematical function which is used to derive the value of Pi(Ï€) in C++. Method 1: Using acos() function: Approach:

1. The value of Î  is calculated using acos() function which returns a numeric value between [-Î , Î ].
2. Since using acos(0.0) will return the value for Î /2. Therefore, to get the value of Î :
double pi = 2*acos(0.0);
1. Now the value obtained from above equation is estimated as:
printf("%f\n", pi);

Below is the implementation of the above approach:

## CPP

 // C++ program for the above approach   #include "bits/stdc++.h" using namespace std;   // Function that prints the // value of pi void printValueOfPi() {       // Find value of pi using     // acos() function     double pi = 2 * acos(0.0);       // Print value of pi     printf("%f\n", pi); }   // Driver Code int main() {     // Function that prints     // the value of pi     printValueOfPi();     return 0; }

Output:

3.141593

Time Complexity: O(1)

Auxiliary Space: O(1)

Method 2: Using asin() function: Approach:

1. The value of Î  is calculated using asin() function which returns a numeric value between [-Î , Î ].
2. Since using asin(1.0) will return the value for Î /2. Therefore, to get the value of Î :
double pi = 2*asin(1.0);
1. Now the value obtained from above equation is estimated as:
printf("%f\n", pi);

Below is the implementation of the above approach:

## CPP

 // C++ program for the above approach   #include "bits/stdc++.h" using namespace std;   // Function that prints the // value of pi void printValueOfPi() {       // Find value of pi using     // asin() function     double pi = 2 * asin(1.0);       // Print value of pi     printf("%f\n", pi); }   // Driver Code int main() {     // Function that prints     // the value of pi     printValueOfPi();     return 0; }

Output:

3.141593

Time Complexity: O(1)

Auxiliary Space: O(1)

Method 3: Using inbuilt constant value define in the “cmath” library: The value of Pi(Ï€) can directly written using the constant stored in cmath library. The name of the constant is M_PI. Below is the program for printing the value of Pi:

## CPP

 // C++ program for the above approach #include "cmath" #include "iostream" using namespace std;   // Function that prints the // value of pi void printValueOfPi() {     // Print value of pi     printf("%f\n", M_PI); }   // Driver Code int main() {     // Function that prints     // the value of pi     printValueOfPi();     return 0; }

Output:

3.141593

Time Complexity: O(1)

Auxiliary Space: O(1)

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